Ring gear mounting arrangement with oil scavenge scheme

ABSTRACT

A gas turbine engine according to an example of the present disclosure includes, among other things, a propulsor section including a propulsor supported on a propulsor shaft, a turbine section including a turbine shaft, and an epicyclic gear train interconnecting the propulsor shaft and the turbine shaft. The epicyclic gear train includes a sun gear coupled to the turbine shaft, intermediary gears arranged circumferentially about and meshing with the sun gear, a carrier supporting the intermediary gears, and a ring gear including first and second portions each having an inner periphery with teeth intermeshing with the intermediate gears. The first and second portions have axially opposed faces abutting one another at a radial interface and respective flanges extending along the radial interface radially outward from the teeth. The first and second portions define a trough axially between and separating the teeth of the first portion from the teeth of the second portion. The first and second portions include facing recesses that form an internal annular cavity along the radial interface.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/038,724 filed Sep. 30, 2020, which is a continuation of U.S. patentapplication Ser. No. 16/819,322 filed Mar. 16, 2020, which is acontinuation of U.S. patent application Ser. No. 16/166,251 filed Oct.22, 2018, now U.S. Pat. No. 10,951,047 granted Mar. 17, 2020, which is acontinuation of U.S. patent application Ser. No. 15/954,832 filed onApr. 17, 2018, now U.S. Pat. No. 10,125,858 granted Nov. 13, 2018, whichis a continuation of U.S. patent application Ser. No. 15/691,259 filedon Aug. 30, 2017, now U.S. Pat. No. 9,951,860 granted Apr. 24, 2018,which is a continuation of U.S. patent application Ser. No. 15/380,570filed on Dec. 15, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/287,813, filed on May 27, 2014, which is nowU.S. Pat. No. 9,657,572 granted May 23, 2017, which is a continuation ofU.S. patent application Ser. No. 11/504,220, filed on Aug. 15, 2006,which is now U.S. Pat. No. 8,753,243 granted Jun. 17, 2014.

BACKGROUND

This disclosure relates to a ring gear used in an epicyclic gear trainof a gas turbine engine.

Gas turbine engines typically employ an epicyclic gear train connectedto the turbine section of the engine, which is used to drive the turbofan. In a typical epicyclic gear train, a sun gear receives rotationalinput from a turbine shaft through a compressor shaft. A carriersupports intermediate gears that surround and mesh with the sun gear. Aring gear surrounds and meshes with the intermediate gears. Inarrangements in which the carrier is fixed against rotation, theintermediate gears are referred to as “star” gears and the ring gear iscoupled to an output shaft that supports the turbo fan.

Typically, the ring gear is connected to the turbo fan shaft using aspline ring. The spline ring is secured to a flange of the turbo fanshaft using circumferentially arranged bolts. The spline ring includessplines opposite the flange that supports a splined outercircumferential surface of the ring gear. The ring gear typicallyincludes first and second portions that provide teeth facing in oppositedirections, which mesh with complimentary oppositely facing teeth of thestar gears.

An epicyclic gear train must share the load between the gears within thesystem. As a result, the splined connection between the ring gear andspline ring is subject to wear under high loads and deflection. Sincethe spline connection requires radial clearance, it is difficult to geta repeatable balance of the turbo fan assembly. Balance can alsodeteriorate over time with spline wear.

SUMMARY

In one exemplary embodiment, an epicyclic gear train for a turbineengine includes a gutter with an annular channel. A rotating structureincludes a ring gear. The rotating structure has an aperture that isaxially aligned with the annular channel. Axially spaced apart wallsextend radially outward relative to the rotating structure to define apassageway. The passageway is arranged radially between the aperture andthe annular channel. The walls are configured to inhibit an axial flowof an oil passing from the aperture toward the annular channel.

In a further embodiment of any of the above, the ring gear includeteeth. The passageway is axially offset from a centerline of the teeth.

In a further embodiment of any of the above, the ring gear includesfirst and second portions. The teeth are provided by the first andsecond portions. The teeth on the first portion are angled opposite theteeth on the second portion with respect to the centerline.

In a further embodiment of any of the above, a trough is providedaxially between the teeth on the first and second portions.

In a further embodiment of any of the above, the ring gear is providedby first and second portions.

In a further embodiment of any of the above, the first and secondportions are fastened to one another.

In a further embodiment of any of the above, the gutter has acenterline. The passageway is axially misaligned with the centerline.

In a further embodiment of any of the above, a fixed structure thatsupports the gutter.

In a further embodiment of any of the above, a seal is arranged on eachof axially opposing sides of the ring gear. The seals provide the walls.

In a further embodiment of any of the above, each seal includes aradially outwardly extending knife edge seal. The knife edge seals areconfigured to further inhibit the axial flow of the oil passing from theaperture toward the annular channel.

In a further embodiment of any of the above, the walls are supported bythe rotating structure.

In a further embodiment of any of the above, the gutter has a U-shapedcross-section.

In a further embodiment of any of the above, the walls each include aface that together define the passageway.

In a further embodiment of any of the above, the walls are arrangedradially inward from the gutter.

In another exemplary embodiment, a gas turbine engine includes a fansection and a turbine section. An epicyclic gear train interconnects thefan section and the turbine section. The epicyclic gear train includes agutter with an annular channel. A rotating structure includes a ringgear. The rotating structure has an aperture that is axially alignedwith the annular channel. Axially spaced apart walls extend radiallyoutward relative to the rotating structure to define a passageway. Thepassageway is arranged radially between and axially aligned with theaperture and the annular channel. The walls are configured to inhibit anaxial flow of an oil passing from the aperture toward the annularchannel.

In a further embodiment of any of the above, the ring gear includeteeth. The passageway is axially offset from a centerline of the teeth.

In a further embodiment of any of the above, the ring gear includesfirst and second portions. The teeth are provided by the first andsecond portions. The teeth on the first portion are angled opposite theteeth on the second portion with respect to the centerline.

In a further embodiment of any of the above, a trough is providedaxially between the teeth on the first and second portions.

In a further embodiment of any of the above, the ring gear is providedby first and second portions.

In a further embodiment of any of the above, the first and secondportions are fastened to one another.

In a further embodiment of any of the above, the gutter has acenterline. The passageway is axially misaligned with the centerline.

In a further embodiment of any of the above, a seal is arranged on eachof axially opposing sides of the ring gear. The seals provide the walls.Each seal includes a radially outwardly extending knife edge seal. Theknife edge seals are configured to further inhibit the axial flow of theoil passing from the aperture toward the annular channel.

In a further embodiment of any of the above, the walls are supported bythe rotating structure.

In a further embodiment of any of the above, the walls each include aface that together define the passageway.

In a further embodiment of any of the above, the walls are arrangedradially inward from the gutter.

In a further embodiment of any of the above, the rotating structure isconfigured to rotate about an axis that extends in an axial direction.The axial flow is configured to flow in the axial direction.

In a further embodiment of any of the above, the rotating structureincludes a sun gear coaxial with the axis. Multiple star gears arearranged circumferentially about and meshing with the sun gear. The ringgear is arranged about and intermeshes with the star gears. A carrier isoperatively connected to a fixed structure. The carrier rotationallysupports the star gears.

In a further embodiment of any of the above, the ring gear isoperatively affixed to a shaft. The fan section is operatively connectedto the shaft.

In a further embodiment of any of the above, the ring gear includesholes that extend therethrough that provide the aperture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of a front portion of a gasturbine engine illustrating a turbo fan, epicyclic gear train and acompressor section.

FIG. 2 is an enlarged cross-sectional view of the epicyclic gear trainshown in FIG. 1.

FIG. 3 is an enlarged cross-sectional view of an example ring gearsimilar to the arrangement shown in FIG. 2.

FIG. 4 is a view of the ring gear shown in FIG. 3 viewed in a directionthat faces the teeth of the ring gear in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A portion of a gas turbine engine 10 is shown schematically in FIG. 1.The turbine engine 10 includes a fixed housing 12 that is constructedfrom numerous pieces secured to one another. A compressor section 14having compressor hubs 16 with blades are driven by a turbine shaft 25about an axis A. A turbo fan 18 is supported on a turbo fan shaft 20that is driven by a compressor shaft 24, which supports the compressorhubs 16, through an epicyclic gear train 22.

In the example arrangement shown, the epicyclic gear train 22 is a stargear train. Referring to FIG. 2, the epicyclic gear train 22 includes asun gear 30 that is connected to the compressor shaft 24, which providesrotational input, by a splined connection. A carrier 26 is fixed to thehousing 12 by a torque frame 28 using fingers (not shown) known in theart. The carrier 26 supports star gears 32 using journal bearings 34that are coupled to the sun gear 30 by meshed interfaces between theteeth of sun and star gears 30, 32. Multiple star gears 32 are arrangedcircumferentially about the sun gear 30. Retainers 36 retain the journalbearings 34 to the carrier 26. A ring gear 38 surrounds the carrier 26and is coupled to the star gears 32 by meshed interfaces. The ring gear38, which provides rotational output, is secured to the turbo fan shaft20 by circumferentially arranged fastening elements, which are describedin more detail below.

Referring to FIGS. 3 and 4, the ring gear 38 is a two-piece constructionhaving first and second portions 40, 42. The first and second portions40, 42 abut one another at a radial interface 45. A trough 41 separatesoppositely angled teeth 43 (best shown in FIG. 4) on each of the firstand second portions 40, 42. The arrangement of teeth 43 forces the firstand second portions 40, 42 toward one another at the radial interface45. The back side of the first and second portions 40, 42 includes agenerally S-shaped outer circumferential surface 47 that, coupled with achange in thickness, provides structural rigidity and resistance tooverturning moments. The first and second portions 40, 42 have a firstthickness T1 that is less than a second thickness T2 arranged axiallyinwardly from the first thickness T1. The first and second portions 40,42 include facing recesses 44 that form an internal annular cavity 46.

The first and second portions 40, 42 include flanges 51 that extendradially outward away from the teeth 43. The turbo fan shaft 20 includesa radially outwardly extending flange 70 that is secured to the flanges51 by circumferentially arranged bolts 52 and nuts 54, which axiallyconstrain and affix the turbo fan shaft 20 and ring gear 38 relative toone another. Thus, the spline ring is eliminated, which also reducesheat generated from windage and churning that resulted from the sharpedges and surface area of the splines. The turbo fan shaft 20 and ringgear 38 can be rotationally balanced with one another since radialmovement resulting from the use of splines is eliminated. An oil baffle68 is also secured to the flanges 51, 70 and balanced with the assembly.

Seals 56 having knife edges 58 are secured to the flanges 51, 70. Thefirst and second portions 40, 42 have grooves 48 at the radial interface45 that form a hole 50, which expels oil through the ring gear 38 to agutter 60 that is secured to the carrier 26 with fasteners 61 (FIG. 2).The direct radial flow path provided by the grooves 48 reduces windageand churning by avoiding the axial flow path change that existed withsplines. That is, the oil had to flow radially and then axially to exitthrough the spline interface. The gutter 60 is constructed from a softmaterial such as aluminum so that the knife edges 58, which areconstructed from steel, can cut into the aluminum if they interfere.Referring to FIG. 3, the seals 56 also include oil return passages 62provided by first and second slots 64 in the seals 56, which permit oilon either side of the ring gear 38 to drain into the gutter 60. In theexample shown in FIG. 2, the first and second slots 64, 66 are insteadprovided in the flange 70 and oil baffle 68, respectively.

Although a preferred embodiment of this invention has been disclosed, aworker of ordinary skill in this art would recognize that certainmodifications would come within the scope of this invention. For thatreason, the following claims should be studied to determine the truescope and content of this invention.

What is claimed is:
 1. A gas turbine engine comprising: a propulsorsection including a propulsor supported on a propulsor shaft; a turbinesection including a turbine shaft; a compressor section havingcompressor hubs with blades driven by the turbine shaft about an axis;and an epicyclic gear train interconnecting the propulsor shaft and theturbine shaft, the epicyclic gear train comprising: a sun gear coupledto the turbine shaft such that the sun gear is rotatable about the axis;intermediary gears arranged circumferentially about and meshing with thesun gear; a carrier supporting the intermediary gears; and a ring gearincluding first and second portions, the first and second portions eachhaving an inner periphery with teeth intermeshing with the intermediategears, the first and second portions having axially opposed facesabutting one another at a radial interface, the first and secondportions including respective flanges extending along the radialinterface radially outward from the teeth, the first and second portionsdefining a trough axially between and separating the teeth of the firstportion from the teeth of the second portion, the radial interfaceextending radially outward from the trough relative to the axis, and thefirst and second portions including facing recesses that form aninternal annular cavity along the radial interface.
 2. The gas turbineengine as recited in claim 1, wherein the ring gear is a two-piececonstruction comprising the first and second portions.
 3. The gasturbine engine as recited in claim 2, wherein the teeth of the first andsecond portions are oppositely angled teeth that force the axiallyopposed faces of the first and second portions toward one another at theradial interface in operation.
 4. The gas turbine engine as recited inclaim 3, further comprising oil return passages that each drain oil on arespective side of the ring gear into a gutter, and the gutter alignedwith the radial interface relative to the axis.
 5. The gas turbineengine as recited in claim 4, wherein the epicyclic gear train is a stargear train, and the propulsor shaft is secured to the flanges of thefirst and second portions of the ring gear such that the ring gearprovides a rotational output of the gear train.
 6. The gas turbineengine as recited in claim 5, wherein the first and second portions havegrooves at the radial interface defining a passageway that expels oil inoperation to the gutter.
 7. The gas turbine engine as recited in claim6, wherein each of the intermediate gears is supported on a respectivejournal bearing.
 8. The gas turbine engine as recited in claim 1,wherein the internal annular cavity is radially between the trough andthe flanges relative to the axis.
 9. The gas turbine engine as recitedin claim 8, wherein the ring gear includes at least one passageway thatexpels oil in operation through an aperture, and the first and secondportions have grooves at the radial interface to define the at least onepassageway.
 10. The gas turbine engine as recited in claim 9, whereinthe at least one passageway includes a plurality of passagewayscircumferentially distributed along the radial interface.
 11. The gasturbine engine as recited in claim 9, wherein the epicyclic gear trainincludes a gutter having an annular channel, and the aperture expels oilto the annular channel in operation.
 12. The gas turbine engine asrecited in claim 11, wherein the aperture is axially aligned with theannular channel with respect to the axis.
 13. The gas turbine engine asrecited in claim 12, wherein the at least one passageway includes afirst segment and a second segment established by the grooves, the firstsegment interconnects the trough and the annular cavity, and the secondsegment interconnects the annular cavity and the aperture.
 14. The gasturbine engine as recited in claim 13, wherein opposed sidewalls of thefacing recesses establish a first width of the annular cavity relativeto the axis, a second width is established across the trough between theteeth of the first and second portions relative to the axis, and thefirst width is greater than the second width.
 15. The gas turbine engineas recited in claim 13, wherein the ring gear is a two-piececonstruction comprising the first and second portions.
 16. The gasturbine engine as recited in claim 15, wherein the teeth of the firstand second portions are oppositely angled teeth that force the axiallyopposed faces of the first and second portions toward one another at theradial interface in operation.
 17. The gas turbine engine as recited inclaim 16, wherein the trough extends radially outward of the teethrelative to the axis.
 18. The gas turbine engine as recited in claim 16,further comprising oil return passages that each drain oil on arespective side of the ring gear into the gutter.
 19. The gas turbineengine as recited in claim 18, wherein the oil return passages extendalong the respective flanges of the first and second portions.
 20. Thegas turbine engine as recited in claim 19, wherein the at least onepassageway includes a plurality of passageways circumferentiallydistributed along the radial interface.
 21. The gas turbine engine asrecited in claim 20, wherein walls of the ring gear inhibit axial flowof oil passing from the aperture towards the annular channel inoperation.
 22. The gas turbine engine as recited in claim 20, whereinthe annular cavity includes a pair of radially outwardly facing wallsprovided by respective ones of the facing recesses, and the pair ofradially outwardly facing walls slope radially inwards from the opposedsidewalls of the annular cavity to an apex along the radial interfacewith respect to the axis to establish a V-shaped geometry.
 23. The gasturbine engine as recited in claim 15, wherein: the epicyclic gear trainis a star gear train, the propulsor shaft includes a radially outwardextending flange secured to the flanges of the first and second portionsof the ring gear; and the carrier is fixed to a housing by a torqueframe.
 24. The gas turbine engine as recited in claim 23, furthercomprising oil return passages that each drain oil on a respective sideof the ring gear into the gutter.
 25. The gas turbine engine as recitedin claim 24, wherein the oil return passages extend along the respectiveflanges of the first and second portions, and the at least onepassageway is axially spaced apart from the oil return passages relativeto the axis.
 26. The gas turbine engine as recited in claim 25, whereinback sides of the first and second portions each have a generallyS-shaped outer circumferential surface that provide a first thicknessand a second thickness, the flanges of the first and second portionsextend radially outwardly from the respective outer circumferentialsurface relative to the axis, the first thickness is established by arespective sidewall of the ring gear, and the second thickness isestablished adjacent to a base of the respective flange such that thesecond thickness is greater than the first thickness.
 27. The gasturbine engine as recited in claim 26, wherein the teeth of the firstand second portions are oppositely angled teeth that force the axiallyopposed faces of the first and second portions toward one another at theradial interface in operation.
 28. The gas turbine engine as recited inclaim 27, further comprising an oil baffle secured to the flanges of thering gear and the propulsor shaft, wherein one of the oil returnpassages is established between the flange of the second portion and theoil baffle.
 29. The gas turbine engine as recited in claim 28, whereinthe propulsor shaft and the ring gear are rotationally balanced with oneanother.
 30. The gas turbine engine as recited in claim 28, furthercomprising seals arranged on axially opposing sides of the ring gear,and wherein the seals inhibit axial flow of oil passing from theaperture towards the annular channel in operation.